Definition of rotations in global frame of reference a

  1. Daniel Kharlamov

    Dear all,


    please help! I've coupled my panel code with GEBT and it seems to work. However, I am missing somehow nearly 30% of the deflection.


    1) How are the rotations defined in global frame of reference, which are written for every node? I am using rotation matrices in my code to rotate the VLM nodes:

    Rx(ang_x)*Ry(ang_y)*Rz(ang_z). Is that correct?


    2) Is someone here, who is knowledeable in aeroelasticity? When I rerun gebt with updated nodal forces, do I need to set also initial deformations and rotations, or can I assume them as zero in GEBT?


    3) By the way, is there a shared library of gebt availabe, so I can include it directly into python?


    Thank you for help. :)


    Kind regards,





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    Replying to Daniel Kharlamov

    1. Su Tian

      Hello Daniel,

      1) The output quantities are the Wiener-Milenkovic parameters, which can be used to calculate the rotation tensor. You can check the following paper for more details. (Wang, Q., Yu, W. and Sprague, M. (2013) ‘Geometric Nonlinear Analysis of Composite Beams using Wiener-Milenković Parameters’, in 54th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference. Boston, Massachusetts, pp. 1–14. doi: 10.2514/6.2013-1697.)

      3) There is no shared library of GEBT right now. You can try to build it by yourself since it is open source. There is a tool called 'f2py' ( and see if it works for you.

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      Replying to Su Tian

    2. Daniel Kharlamov

      Thank you for your answer.


      I've tried to build one, but there is a struct as input argument and f2p fails here.


      Kind regards,


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      Replying to Daniel Kharlamov